OPRM1 and acalculous cholecystitis: Cholestasis in hospitalized patients receiving opiates has the potential to have devastating outcomes including acalculous cholecystitis, sepsis, or even death. Methylnaltrexone use is growing in popularity in hospitals over recent years. Its mechanism as a mu-opioid receptor antagonist allows for the selective targeting of gastrointestinal dysmotility. It has been reported that methylnaltrexone also has effects on the sphincter of Oddi and may directly have effects on cholestasis. In this study, we evaluate the outcomes of trauma patients treated with methylnaltrexone.